Social Explorer, U.S. Census Bureau; Census of Population and Housing, 1990: Summary Tape File 3 on CD-ROM [machine-readable data files] / prepared by the Bureau of the Census. Washington: The Bureau [producer and distributor], 1991.

This chapter serves as a guide for data users to both the tape and the technical documentation. Novice users trying to understand how to use the documentation and the file should read this chapter first.

Documentation Chapters

The Abstract chapter in this documentation provides a quick overview of the file, including the formal title, geographic coverage, subject coverage, and file availability. Also shown are citations for related reference materials and printed reports. Their titles and geography are included in this section, along with purchasing information.

The Subject Locator is an aid to finding which tables provide the information needed. The List of Tables (Matrices) and the Table (Matrix) Outlines provide two types of presentations for the tables available in the file. The List of Tables (Matrices) has the table titles and universes.

The Table (Matrix) Outlines offer a detailed presentation of the tables. When reviewing the tables, remember that a colon (:) following an entry indicates the entry is a heading, not a data cell.

Information about file or documentation changes sometimes becomes available after the documentation has been printed. User notes inform the user community about these changes. These are issued in a numbered series. If there are technical documentation changes, revised pages usually accompany them. The revised pages should be inserted in their proper location, but the user note cover sheet should be filed in the User Notes chapter. Technical notes, which contain file errata, are also issued by the Census Bureau. We suggest filing these following appendix I.

The data dictionary describes the file and provides character locations for each variable and each table. It has two elements, the identification section and the table (matrix) section.

In the identification section, the components include the field name; the data dictionary reference name, a short mnemonic for use with software packages; field size; starting position; and data type (alphabetic, numeric, or alphanumeric).

The identification section of the data dictionary is identical for all summary tape files. It provides a list of the geographic codes or refers the user to the appropriate source. Review the footnotes carefully; they provide explanations for various terms. These footnotes are listed at the end of the identification section of the data dictionary.

The table (matrix) section provides information on the table (matrix) number; table (matrix) description; number of implied decimals in each cell (if not 0); starting position within the record, within the segment, and for all cells within the first-level variable; and cell coordinates.

Detailed information on geographic areas is in appendix A followed by subject-matter definitions in appendix B. Appendix C provides detailed statistical information about the data while appendix D outlines the data collection and processing procedures. Facsimiles of both the respondent instructions and 1990 census long-form questionnaire are in appendix E.

Appendix F furnishes detailed information on all the data products of the 1990 census, as well as suggested sources of information and assistance. Map information is included in appendix G.

Appendix H contains the code lists used in processing the data. These are especially helpful in determining the components included in categories such as race or group quarters. These codes are used in conjunction with the table (matrix) outlines and data dictionary chapters. In the file presentation included in those chapters, some cell entries are followed by numeric codes in parentheses. These are the codes included in that cell. For example, in a table including race, the entry for Asian or Pacific Islander is followed by (600-699, 976-985). The code list for race in appendix H identifies all the race codes included in the Asian or Pacific Islander category.

The Census Bureau issues population count corrections on an occasional basis. Count corrections for geography at the place level and above are available from Customer Services, Data User Services Division, Bureau of the Census, Washington, DC 20233. Count corrections for geography at the census tract/BNA level or below are available from Population Division, Bureau of the Census, Washington, DC 20233. When requesting these corrections, please include the desired census tract/BNA, block group, or block numbers.

The file is segmented into 35 dBase III (.DBF) files, designated STF300ss.DBF through STF334ss.DBF where 'ss' is the two-character State abbreviation. The STF300 segment contains the full 67 field identification section. The identification field names are shown in the Data Dictionary chapter of the technical documentation. Segments STF301 through STF334 each contain eight identification fields repeated from the STF300 segment. They are shown below.

Fields in numeric data tables are named according to a convention which identifies the tables and the sequence of the data item within the table. The 63 data items in P88, for example, are identified as P0880001 through P0880063. The one data item in table P107A is identified as P107A001.

Each record on a summary tape file is uniquely identified by a combination of geographic (for example, State, county, and county subdivision), summary level, and geographic component codes. For example, if you have a Maryland STF 3A file and want to look at the summary record for Prince George's County, three identification fields must be checked: the summary level code for county records (050), the total record for geographic components (00), and the county code for Prince George's County (033). If all three fields are not checked, multiple records will be found. See the Summary Level Sequence Charts and Geographic Area Component Codes section below for information on identifying summary level and geographic component codes.

The Summary Level Sequence Charts chapter and the geographic area component codes provide important information for using the 1990 census summary tape files.

The Summary Level Sequence Charts chapter for STF 3 files identifies the geographic levels for which data are provided. It is easy to determine this if you remember that the last geographic area type listed in the sequence identifies the geography of the summary level; the prior codes simply define the hierarchy. For example, in summary level 140, the hierarchy listed is State-county-census tract/block numbering area (BNA). The record actually contains data for a census tract/BNA within a given county and State.
When reading the Summary Level Sequence Charts chapter, it is important to recognize that dashes (--) separate the individual hierarchies while slashes (/) separate different types of geography within the same hierarchy.

After identifying the summary level code, turn to chart 1 at the end of this chapter to determine the geographic area codes and area characteristics provided on CD-ROM for this summary level. Remember that an asterisk (*) indicates a code in that field. The code may be one of the standard codes described below.

The Summary Level Sequence Charts chapter also provides geographic component code information. This code identifies the various geographic components for which the record is repeated within the summary level. These component codes are provided in the data dictionary beginning in position 14. For example, the Summary Level Sequence Chart for STF 3A indicates that the summary level for State records (040) has geographic component codes 00, 40, 42, 43, and 44. By turning to the geographic component variable in the data dictionary, you can determine that the tables for summary level 040 (State) are available for total geography (State) (geographic component=00), American Indian reservation and trust land (geographic component=40), tribal jurisdiction statistical area (geographic component=42), tribal designated statistical area (geographic component=43), and Alaska Native village statistical area (Alaska only) (geographic component=44).

In short, always check the geographic codes, the summary level (beginning in position 11 of the data dictionary), and the geographic component code (beginning in position 14 of the data dictionary) for complete identification of an STF 3 record. SPECIAL AREA CODES Special area codes appear in the geographic area codes portion of the data dictionary (positions 142-171) on all STF's. The codes represented may vary across STF's. In STF 3 CD-ROM files special area code (1), and special area code (9) are used. The codes are described below. Special area code (9) is used in all summary levels except 800, 810, and 820.

In STF 3B files only, special area code 1 is used. It contains the 5-digit ZIP Code.

In the identification section of all STF's, there are standard codes, undefined in the data dictionary, that have identical meaning regardless of the field. The codes are the same size as the field; that is, a three-character field will have three symbols. These standard codes are listed below.

! Not available --The code would be shown except it had not been determined when the files were prepared (for example, metropolitan area code on a county summary level (050) on STF 1A).

9 Not in --This indicates a "remainder of" an area, such as a place code in the portion of a county subdivision not in a place, or the summary level is not part of any area to which the code field applies, such as a summary level which is not in an Alaska Native Regional Corporation.

Blank Not applicable --This indicates that the code is not applicable to the summary level.

Where these codes are specifically defined in the data dictionary, the defined code should be used. For example, in the division code description on the data dictionary (position 89), the code for the Pacific Division is indicated as "9." This "9" should be interpreted as the division code, not as "not in," the standard code for "9."